The present invention relates to a gas dosimeter for colorimetrically indicating the presence of total amines in solution or in air. Particularly, this invention relates to a gas dosimeter utilizing 1,2 naphthoquinone-4-sulfonic acid and derivatives thereof as the colorimetric reagent.
Aniline and other amines are an important class of chemicals which are widely used in various industries such as plastics, textiles, pharmaceuticals, dyes, etc. Because of increasing concern over safety and health hazards presented by exposure to amine vapors in air, industries require an effective and reliable way to monitor amine levels in the workplace environment and to detect exposure to potentially hazardous amine concentrations. Monitoring devices in the form of dosimeter badges have been developed for monitoring various toxic vapors such as formaldehyde, oxides of nitrogen, ethylene oxide, hydrogen sulfide and ammonia. Exemplary dosimeters are disclosed in U.S. Pat. Nos. 3,681,027 to Smith; 3,992,153 to Ferber et al; 4,063,452 to Bradshaw; 4,327,575 to Locker; 4,348,358 to McKee et al; and 4,495,291 to Lawton. However, currently there are no dosimeter badges available for monitoring exposure to amine vapors.
Typically, the measurement of amine vapors has required laboratory colorimetric analysis methods. Several reagents applicable in the laboratory for colorimetric determination of amines have been described in the literature. The basic method involves passing a known quantity of gas through an absorbing solution containing a colorimetric reagent and monitoring the change in color of the solution which is a function of the concentration of the amine in the absorbing solution. Several examples are described in Table 1 below.
TABLE 1 ______________________________________ Published Colorimetric Reagents for the Determination of Amines In Solution Process or Reagent Comments References* ______________________________________ Diazotation Specific to aromatic 1-2 amines. The method is sensitive; however difficult to apply quantitatively. Aromatic Very sensitive when 3-4 Substitutions fluorescence is used. Most common. Reagents are typically 2,4 dinitrochlorobenzene or naphthalene Imines Formation The aldehyde of choice is 4-5 With Aldehydes and N, N--dimethylamino Ketones p-benzaldehyde. Red color is formed. Hydrazines interfere. O--Quinones Sensitive and selective. 6-7 The reagent is unstable. ______________________________________ *References ______________________________________ 1. Seggia, S. and Hammer, J. G., "Quantitative Organic Analysis Via Functional Groups", 4th Ed., John Wiley and Sons, New York (1979). 2. Bordelin, F. J. and Kemp, C. R., Ind. Eng. Chemical Analysis, 18, 420 (1946). 3. Smilts, F. J. and Jones, E., "A Scheme of Qualitative Organic Analysis", London (1953). 4. Higuchi, T. and Bodin, J., "Pharmaceutical Analysis", T. Higuchi and E. H. Brochmann (Eds.), Wiley Interscience, New York (1951). 5. Menzie, C., Anal. Chem., 28, 1321-22 (1956). 6. Frame, E. G., Russell, J. A. and Whilhelm, A. J., J. Block, Chem. 255, 1949 (1943). 7. Auerbach, M.E., "Drug Standards", 20, 165 (1952). ______________________________________
However, the above-noted known processes and colorimetric reagents all suffer from at least one of the following disadvantages:
1. They form color very slowly. PA0 2. The reagents are unstable. PA0 3. The reagents cannot be easily used in the field, namely they cannot be used in a dosimetry badge. PA0 4. The reagents cannot be adapted to dry-chemistry application. PA0 5. The reagents are non-selective to amines.
The present invention provides a colorimetric reagent useful in a gas dosimeter so that the presence of amines can be visually shown. Moreover, the reagent can be utilized to differentiate between total amines and aromatic amines through the use of a buffering solution. The availability of a colorimetric reagent which can visually show the presence of total amines or aromatic amines alone and which is adaptable for use in a gas dosimeter can help even unskilled personnel determine whether they are present in a dangerous environment.